Naoyuki Tamura(University of Durham)

The Universe at Redshifts from 1 to 2

for Early-Type Galaxies~ Unveiling “Build-up Era” with FMOS ~

Outline

Summary

Galaxy population at z < 1 and z > 2

To understand the histories ofearly-type galaxies …Does stellar population tell us all ?

What are expected at 1 < z < 2 ?

Revisit the starting point :

How can the strengths of Subaru/FMOS be exploited ?

Extremely Red ObjectsLimitation due to lack of spectrum

NGC 3923 : E4SFR

tEvolutions of CM relation & Fundamental Plane up to z ~ 1 look passive.

No active star formation is on-going at z=0. The bulk of stars seem to be old.

Stars in Elliptical Galaxies

Star formation Passiveevolutionstopped.

z > 2 ?

Ages at z = 0 from spectroscopy

[km/s] 100 200 300 [km/s]

60 100 180

Trager et al. (2000)

Caldwell et al. (2003)

Cluster Group

Field Virgo

Field

What does “age” tell us ?

“Galaxy formation history”

- when did a galaxy become an elliptical ?

“Star formation history”

- when did most of the stellar content form ??

Monolithic Collapse ScenarioStarburst

Gas rich

Hierarchical Merging ScenarioMajor mergerLuminosity

Function

Stellar Population

Luminosity Function of E/S0s at z < 1COMBO-17~ 2800 arcmin^2, R < 26 (5), ~ 25000 galaxies

~ 5000 galaxies on the red sequence at 0.2 < z < 1.2.

Rix et al. (2004)

GEMSHigh resolution imaging follow-up with ACS/HST

Most of them (~ 85 %) seem to be morphologically early-type.

Evolution of luminosity function

Luminosity Function of E/S0s at z < 1COMBO-

17

Bell et al. (2003)

About half of the local population were already in place at z ~ 1 ?

Luminosity Function of E/S0s at z < 1

Morphology

Spectroscopy

Multi-band photometry

Im et al. (2002): DEEP Groth Strip survey

Chen et al. (2003): Las Campanas IR survey

Pozzetti et al. (2003): K20 survey

Suggest a mild evolution up to z ~ 150 ~ 80 % were already in place at z

~ 1 ?

(HST/WFPC2 images)

Any “bona-fide” E/S0s at z > 2 ?

Radio galaxies

Rocca-Volmerange et al. (2004)

Pentericci et al. (2001)

(z = 2.3)

(z = 2.4)

Passive evolution prediction

(z = 10, M = 10 M )

f12

Any “bona-fide” E/S0s at z > 2 ?

Lyman Break GalaxiesSCUBA Galaxies

Red galaxies from FIRES

No clear Hubble sequence ?A population of passive E/S0s have not revealed

yet ?

Stellar mass ~ 10 M

J-K ~ 2 or redder

z = 2 ~ 3 (?)

z > 3

Strong clustering

<z> ~ 2.5 (1 < z < 4)SFR ~ 1000 M /yr

SFR ~ 1 - 100 M /yr

Starburst galaxies ?

10

Investigations are on-going ...

How can they be linked at z = 1 ~ 2 ? Star forming

galaxies Passive evolution phase

Luminosity function of passive galaxiesand its evolution at z = 1 ~ 2 A number of post-starburst galaxies ?

Half or more of the local population show up in this epoch ?

Consumption ?

Distant clusters are revealed ?

Through redshift survey …

somehowEnvironmental effect ?

Extremely Red Objects (EROs)

Good candidates for passive ellipticals at z > 1.

Heterogeneity Although the colour criterion seems to

work for isolating passive ellipticals …

Luminosity function of EROs has been studied.Our understandings of EROs have

been limited due to lack of spectra.

R-K > 5 / I-K > 4

(Cimatti et al. 2003; Yan et al. 2004)

Smith et al. (2002)

Smail et al. (2002)

Mannucci et al. (2002)

Colour criterion to classify EROs Cimatti et al.

(2003)

Miyazaki et al. (2002)

Caputi et al. (2004)

Evolution of ERO LF at z > 1 ?

Extremely Red Objects (EROs)

Good candidates for passive ellipticals at z > 1.

Heterogeneous Although the colour criterion seems to

work for isolating passive ellipticals …

Luminosity function of EROs has been studied.

Photo-z : z ~ 0.3 at z ~ 1.5

Our understandings of EROs have been limited due to lack of spectra.

Too coarse to investigate evolution at 1 < z < 2 ?

R-K > 5 / I-K > 4

(Cimatti et al. 2003; Yan et al. 2004)

What we need to do are :To perform deep spectroscopic

observations and to get quality data.

Redshift

ClassificationAbsorption line

To collect a large number of galaxies at z > 1 from a large survey area.

Good statistics Cosmic variance

The other word of FMOS (1)Wide spectral coverage in the NIRSpectral features in the rest frame optical

are available for galaxies at z > 1.

Combination with UKIDSS-DXS

Optimal for redshift survey.

(& Subaru/Suprime-Cam)

Allows us to efficiently pick up candidates for galaxies at z > 1 with colour information.

Luminosity can be derived with the aid of redshift.

The other word of FMOS (2)Wide field & high multiplicity

30’

FMOS-FOV / 400 fibres

~ 200 fibres will be available for objects in one exposure.

Better statisticsLonger integration

Highly efficient !

Simulated Spectrum

H = 20.5 mag

Old stellar population (3.0 Gyr age) at z = 1.5

8 hr integration (1 hr x 8) & 5 pix. binning

4000 A

G-band

H

Mgb

Gemini Deep Deep Survey

4 x 30 arcmin^2 fieldNod & shuffle technique

Gemini Multi-Object Spectrograph

> 30 hr integration per field

Fibre Multi-Object SpectrographFOV ~ 700

arcmin^2200/200 fibres for object/sky(+ Double beam switching obs. ?)??? hr integration per

FOV

???????????????? Survey

Simulated Spectrum

H = 22.0 mag

Old stellar population (3.0 Gyr age) at z = 1.5

100 hr integration (1 hr x 100) & 5 pix. binning

4000 A

G-band

H

MgbNaD

Summary

Luminosity function of passive galaxies Evolution of LF between z = 1

and 2.A number of post-starburst galaxies ?

To understand history of early-type galaxyLuminosity

FunctionStellar Population

Bridging two epochs ? z <

12 < z

Need to look at absorption lines

Star forming galaxiesPassive evolution

Wide field & high multiplicity can beexploited for deep observation.